Material for gland packing and the gland packing

ABSTRACT

A strip-like expanded graphite ( 3 ) is disposed on one face of a sheet-like reinforcing member ( 20 ) configured by a fibrous material ( 2 ) to form a strip-like base member ( 4 ). The base member ( 4 ) is stranded to be formed as a cord-like member ( 40 ). The outside of the cord-like member ( 40 ) is covered by a portion of the strip-like expanded graphite ( 3 ), and the whole reinforcing member ( 20 ) and the remaining portion of the strip-like expanded graphite ( 3 ) are involved in the cord-like member ( 40 ). A large number of openings ( 20 A) are formed in the reinforcing member ( 20 ). The strip-like expanded graphite ( 3 ) faces the openings ( 20 A). The strip-like expanded graphite ( 3 ) is engaged with the openings ( 20 A), whereby the coupling force between the strip-like expanded graphite ( 3 ) and the reinforcing member ( 20 ) is enhanced.  
     The gland packing material ( 1 ) is provided by the fibrous material with high tensile strength, and easily subjected to a braiding or twisting process. Furthermore, the gland packing material ( 1 ) has a high shape-retaining property, and exerts a high sealing property that is originally possessed by an internal reinforcement structure. Moreover, the used amount of an adhesive agent can be reduced, and reduction of the sealing property due to hardening or burning of the adhesive agent can be avoided.

TECHNICAL FIELD

The present invention relates to a gland packing material which isuseful in production of a gland packing, and also to a gland packingwhich is produced by the gland packing material.

BACKGROUND ART

Conventionally, as a gland packing material which is useful inproduction of a gland packing, for example, known is a materialdisclosed in Japanese Patent No. 3,101,916.

In the conventional art, as shown in FIG. 21, for example, expandedgraphite (52) is bonded by an adhesive agent to both faces of aplurality of reinforcing fiber yarns (51), thereby forming a glandpacking material (50) in which the interior is reinforced (hereinafter,such reinforcement is referred to as internal reinforcement).

The conventional gland packing material (50) is provided with hightensile strength by the reinforcing fiber yarns (51), and hence can besubjected to a braiding or twisting process. When a plurality of suchgland packing materials (50) are bundled, and then a braiding ortwisting process is applied to the bundle, therefore, a gland packingcan be produced. When eight gland packing materials (50) are bundled andan eight-strand square-knitting process is conducted, for example, agland packing (53) which is braided as shown in FIG. 22 is produced,and, when six gland packing materials (50) are bundled and a twistingprocess is applied, a gland packing (53) which is twisted as shown inFIG. 23 is produced.

Each of the conventional gland packings (53) is provided by the expandedgraphite (52) with properties which are preferable in sealing, and whichare inevitable in a packing, such as the compressibility and therecovery property, and hence can seal a shaft seal part of a fluidapparatus while producing a high sealing property.

In the conventional gland packing material (50) having the internalreinforcement, however, the expanded graphite (52) which covers the bothfaces of the reinforcing fiber yarns (51) is not expected to exert ahigh shape-retaining property. When the gland packing (53) is producedwith using such a gland packing material (50) having the poorshape-retaining property, the expanded graphite (52) may drop off duringthe braiding or the twisting process. Therefore, the elasticity of thegland packing (53) is reduced, the properties which are preferable insealing, such as the compressibility and the recovery property are lost,and the sealing property of the gland packing (53) is lowered.

A large amount of adhesive agent is used in order to bond thereinforcing fiber yarns (51) and the expanded graphite (52) together.Therefore, the properties of the expanded graphite (52) such as theaffinity and the compression recovery property are lowered by hardeningof the adhesive agent, thereby adversely affecting the sealing property.When the gland packing (53) produced by the gland packing material (50)is used under a high temperature condition, the adhesive agent may beburned, thereby causing a possibility that penetration leakage isincreased and the sealing property is reduced.

The invention has been developed in view of the above-describedcircumstances. It is an object of the invention to provide a glandpacking material which is provided with high tensile strength by afibrous material that reinforces the interior, which can be easilysubjected to a braiding or twisting process, which can obtain a highshape-retaining property, and in which a high sealing property that isoriginally possessed by an internal reinforcement structure is notimpaired, and reduction of the sealing property due to hardening orburning of an adhesive agent can be avoided, and a gland packing whichis produced with using the gland packing material.

DISCLOSURE OF THE INVENTION

In order to attain the object, for example, the invention is configuredin the manner which will be described with reference to FIGS. 1 to 20showing embodiments of the invention.

Namely, the invention relates also to a gland packing material, and ischaracterized in that the material is configured by a cord-like member(40) which is formed by stranding a strip-like base member (4), orwinding a strip-like base member (4) about a longitudinal direction, orwinding a strip-like base member (4) about a longitudinal direction andthen stranding the base member, the base member (4) comprises: areinforcing member (20) configured by a fibrous material (2); and astrip-like expanded graphite (3), the strip-like expanded graphite (3)is disposed at least on one face of the reinforcing member (20), aportion of the strip-like expanded graphite (3) is placed outside thecord-like member (40), the reinforcing member (20) is involved in thecord-like member (40), a large number of openings (20A) are formed inthe reinforcing member (20), and the strip-like expanded graphite (3)faces the openings (20A).

The invention relates to a gland packing, and is characterized in that aplurality of the gland packings (1) are used, and braided or twisted.

According to the configuration, the invention has the followingadvantages.

The cord-like member has an internal reinforcement structure in whichthe strip-like expanded graphite is placed on an outer side, and thesheet-like reinforcing member configured by a fibrous material is placedinside, and which is surely reinforced by the reinforcing member.

Moreover, the many openings are formed in the reinforcing member, andthe strip-like expanded graphite faces the openings. Therefore, aso-called anchor effect in which the expanded graphite is engaged withthe openings is produced. Because of the anchor effect, the couplingforce between the strip-like expanded graphite and the reinforcingmember is enhanced, and hence the shape-retaining property of the glandpacking material is high. As a result, even when a used amount of anadhesive agent for coupling the strip-like expanded graphite with thereinforcing member is restricted to zero or a very small amount, thereinforcing member is hardly separated from the strip-like expandedgraphite during braiding or a twisting process of producing a glandpacking, and the internal reinforcement effect due to the reinforcingmember can be effectively exerted.

Since the used amount of an adhesive agent can be restricted to zero ora very small amount, it is possible to suppress the properties of thestrip-like expanded graphite such as the affinity and the compressionrecovery property from being lowered by hardening of the adhesive agent.

Since the reinforcing member and the strip-like expanded graphite arepartly involved in the cord-like member, the reinforcing member ishardly separated from the strip-like expanded graphite during braidingor a twisting process of producing a gland packing, so that theshape-retaining property of the gland packing material can be enhancedand the internal reinforcement effect can be effectively exerted.

Since the reinforcing member is involved in the cord-like member, asandwich structure in which a portion of the strip-like expandedgraphite is sandwiched by the reinforcing member is formed, so that, inthe case where the packing is compressed or a pressure is applied to thepacking, movement of expanded graphite particles is suppressed.Therefore, the shape-retaining property of the gland packing materialcan be further improved.

Moreover, properties which are preferable in sealing, such as thecompressibility and the recovery property are produced by the strip-likeexpanded graphite, and the strip-like expanded graphite is placedoutside the cord-like member. Therefore, the gland packing material canobtain a high sealing property.

The gland packing material has a high sealing property and an excellentshape-retaining property. In a gland packing which is produced withusing a plurality of such gland packing materials, therefore, theexpanded graphite is prevented from dropping off during the braiding orthe twisting process. As a result, in the gland packing, the elasticityis not reduced, and the properties which are preferable in sealing, suchas the compressibility and the recovery property can be held. In thecase where the packing is compressed or a pressure is applied to thepacking, movement of expanded graphite particles is suppressed.Therefore, the sealing face pressure is prevented from being lowered, sothat the pressure resistance performance can be improved, and thepressure contact force to be applied to the counter member is kept to ahigh level, so that the sealing property can be improved. As a result,the gland packing can satisfactorily seal a shaft seal part of a fluidapparatus or the like.

In the gland packing material, moreover, the used amount of an adhesiveagent can be restricted to zero or a very small amount. Even when thegland packing using the gland packing material is used under a hightemperature condition, reduction of the sealing property due to burningof the adhesive agent can be suppressed.

In the cord-like member, only a portion of the outer side may be coveredby the strip-like expanded graphite. When a whole outside of thecord-like member is covered by the strip-like expanded graphite,however, the properties of the strip-like expanded graphite which arepreferable in sealing can be exerted more effectively.

The strip-like expanded graphite may be disposed only on one face of thereinforcing member. Alternatively, the strip-like expanded graphite maybe disposed on both faces of the reinforcing member. In this case, adouble structure in which the strip-like expanded graphite sandwichesthe reinforcing member is formed, and hence the properties which arepreferable in sealing, such as the compressibility and the recoveryproperty are further improved, so that a higher sealing property can beobtained. Since the strip-like expanded graphite is disposed on the bothfaces of the reinforcing member, the contact area between thereinforcing member and the strip-like expanded graphite is widened, andthe coupling force between the strip-like expanded graphite and thereinforcing member can be further enhanced through the many openingsdisposed in the reinforcing member.

For example, the sheet-like reinforcing member configured by a fibrousmaterial may be configured by a fiber-opened sheet in whichmultifilament yarns are opened in a sheet-like shape.

In this case, a thickness of the fiber-opened sheet is preferably set to10 μm to 300 μm, and more preferably to 30 μm to 100 μm. According tothe configuration, the fiber-opened sheet can be easily produced, thesheet can be easily stranded, and the internal reinforcement effect canbe enhanced.

As the fibrous material, one or two or more selected from the groupconsisting of carbon fibers and other brittle fibers, and tough fibersmay be used. When each fiber is excessively thin, such a fibrousmaterial may be broken during a stranding process, and, when each fiberis excessively thick, the fibrous material is hardly stranded.Therefore, the diameter of each fiber is preferably 3 μm to 15 μm, andmore preferably in a range of 5 μm to 9 μm.

In the case where carbon fibers or brittle fibers are used as thefibrous material, the tensile strength is high, and an excellent heatresistance can be attained. In the case where carbon fibers are used,particularly, these performances can be exerted more satisfactorily. Inthe case where other brittle fibers are used, the invention can beeconomically implemented.

Specific examples of the brittle fibers are glass fibers, silica fibers,and ceramic fibers such as alumina and alumina-silica. One or two ormore selected from the group consisting of these fibers can be used.

In the case where tough fibers are used as the fibrous material, thefibrous material can be easily produced with using thin fibers becausethe fibers have high bendability and exert excellent workability. Aneconomical gland packing material can be provided because the fibershave high productivity. When such a gland packing material is used, notonly a gland packing having a large diameter, but also a gland packinghaving a small diameter can be easily produced, and moreover it ispossible to produce a gland packing which has high durability, and whichis economical.

Furthermore, specific examples of the tough fibers are metal fibers,aramid fibers, and PBO (poly-p-phenylenebenzobisoxazole) fibers. One ortwo or more selected from the group consisting of these fibers can beused.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 20 show embodiments of the invention.

FIGS. 1 to 6 show a first embodiment of the gland packing material ofthe invention, FIG. 1 is a perspective view of the gland packingmaterial, FIG. 2 is a partial enlarged plan view showing a state whereexpanded graphite faces many openings of a reinforcing member configuredby a fibrous material, FIG. 3 is a section view taken along the line A-Ain FIG. 2, FIG. 4 is a perspective view showing a fiber bundle, FIG. 5is a perspective view showing a fiber-opened sheet, and FIG. 6 is aperspective view of a base member.

FIG. 7 is a perspective view of strip-like expanded graphite in a statewhere a small amount of adhesive agent is used, and showing amodification of a procedure of producing the base member.

FIGS. 8 and 9 show another modification of the procedure of producingthe base member, FIG. 8 is a section view showing a state where expandedgraphite powder is superimposed on a fiber-opened sheet, and FIG. 9 is asection view of the base member.

FIGS. 10 to 12 show modifications of the base member in the firstembodiment, FIG. 10 is a section view of a base member in a firstmodification, FIG. 11 is a section view of a base member in a secondmodification, and FIG. 12 is a section view of a base member in a thirdmodification.

FIG. 13 is a perspective view showing a second embodiment of the glandpacking material of the invention.

FIGS. 14 and 15 show a third embodiment of the gland packing material ofthe invention, FIG. 14 is a section view of a base member, and FIG. 15is a perspective view of the gland packing material.

FIGS. 16 and 17 show modifications of the base member in the thirdembodiment, FIG. 16 is a section view of a base member in a firstmodification, and FIG. 17 is a section view of a base member in a secondmodification.

FIG. 18 is a perspective view showing a fourth embodiment of the glandpacking material of the invention.

FIG. 19 is a perspective view showing an embodiment of the gland packingof the invention.

FIG. 20 is a perspective view showing another embodiment of the glandpacking of the invention.

FIGS. 21 to 23 show the conventional art.

FIG. 21 is a perspective view of a gland packing material of theconventional art.

FIG. 22 is a perspective view of a gland packing which is formed bybraiding the gland packing material of the conventional art, and FIG. 23is a perspective view of a gland packing which is formed by twisting thegland packing material of the conventional art.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the invention will be describedwith reference to the drawings.

FIG. 1 is a perspective view showing a first embodiment of the glandpacking material of the invention. Referring to the figure, the glandpacking material (1) is configured by a cord-like member (40) which isformed by sequentially stranding a strip-like base member (4) in thelongitudinal direction with starting from an end. The base member (4)comprises: a sheet-like reinforcing member (20) configured by many longcarbon fibers (2) which are very thin; and a strip-like expandedgraphite (3). The reinforcing member (20) is disposed on one face of thestrip-like expanded graphite (3). The stranding process is applied sothat the strip-like expanded graphite (3) is directed outward, and thereinforcing member is directed inward. As a result of the strandingprocess, the whole reinforcing member (20) and one end portion (5) inthe width direction of the strip-like expanded graphite (3) are involvedin the cord-like member (40). Namely, the cord-like member (40) is inthe state where a portion of the strip-like expanded graphite (3) isplaced in the whole outer side, and the reinforcing member (20) iscovered by the strip-like expanded graphite (3), and the gland packingmaterial (1) is configured to have an internal reinforcement structurein which the sheet-like reinforcing member (20) is interposed betweenthe strip-like expanded graphite (3).

As shown in FIGS. 2 and 3, the reinforcing member (20) comprises a largenumber of openings (20A), and the strip-like expanded graphite (3) facesthe openings (20A). The many openings (20A) are formed in a case wherethe openings are spontaneously formed when the reinforcing member (20)configured by many long carbon fibers (2) which are very thin arestranded, or a case where many portions of the reinforcing member (20)are slightly forcedly torn in such a manner that adjacent carbon fibers(2) are separated from each other, and local clefts are previouslyformed in an artificial manner before the stranding process.

The carbon fibers (2) have a property that they are hardly broken by anexternal force of the level of stranding. Therefore, it is possible toobtain the gland packing material (1) having an internal reinforcementstructure in which the reinforcing member (20) configured by the carbonfibers (2) is covered by the strip-like expanded graphite (3).Furthermore, the strip-like expanded graphite (3) faces the manyopenings (20A) formed in the reinforcing member (20) configured by thecarbon fibers (2), and the strip-like expanded graphite (3) is engagedwith the openings (20A) to produce a so-called anchor effect. Because ofthe anchor effect, the coupling force between the strip-like expandedgraphite (3) and the reinforcing member (20) is enhanced, and hence theuse of an adhesive agent can be omitted. In a process in which the glandpacking material (1) is braided or twisted in order to produce a glandpacking which will be described later, namely, the reinforcing member(20) is hardly separated from the strip-like expanded graphite (3) evenwhen an adhesive agent is not used. Therefore, the shape-retainingproperty of the gland packing material (1) can be enhanced, and theinternal reinforcement effect due to the reinforcing member (20) can beeffectively exerted. The omission of the use of an adhesive agentsuppresses the properties of the strip-like expanded graphite (3) suchas the affinity and the compression recovery property from being loweredby hardening of the adhesive agent.

In the gland packing material (1), the whole reinforcing member (20) andthe one end portion (5) in the width direction of the strip-likeexpanded graphite (3) are involved in the cord-like member (40).According to the configuration also, the reinforcing member (20) ishardly separated from the strip-like expanded graphite (3) when thegland packing is produced, so that the shape-retaining property of thegland packing material (1) can be enhanced and the internalreinforcement effect can be effectively exerted.

The properties which are preferable in sealing, such as thecompressibility and the recovery property are provided by the strip-likeexpanded graphite (3), and the strip-like expanded graphite (3) isplaced outside of the cord-like member. Therefore, the gland packingmaterial (1) can obtain a high sealing property.

Since the whole reinforcing member (20) and a portion of the strip-likeexpanded graphite (3) are involved in the cord-like member (40), asandwich structure in which a portion of the strip-like expandedgraphite (3) is sandwiched by the reinforcing member (20) is formed. Inthe case where the packing is compressed or a pressure is applied to thepacking, therefore, movement of expanded graphite particles issuppressed. Therefore, the shape-retaining property of the gland packingmaterial (1) can be further improved. In the gland packing which isformed by the gland packing material (1), when the packing is compressedor a pressure is applied to the packing, movement of expanded graphiteparticles is suppressed. Therefore, the sealing face pressure isprevented from being lowered, so that the pressure resistanceperformance can be improved, and the pressure contact force to beapplied to the counter member is kept to a high level, so that thesealing property can be improved.

For example, the gland packing material (1) can be produced in thefollowing procedure.

First, the base member (4) is formed in the following procedure.

As shown in FIG. 4, initially, a multifilament yarn in which, forexample, 12,000 carbon fibers (2) each having a diameter of 7 μm arebundled is used to form a carbon fiber bundle (2A) in which the fibersare bundled in a flat shape having a width (W)=4.00 mm and a thickness(T)=0.20 mm. Then, the carbon fiber bundle (2A) is fiber-opened to asheet-like shape so as to be extended in the width direction, whereby afiber-opened sheet (2B) having a width (W1)=25.00 mm and a thickness(T1)=0.03 mm is formed as shown in FIG. 5.

For example, the fiber opening process is conducted in the followingmanner. First, the carbon fiber bundle (2A) is heated to soften a sizingagent for the fiber bundle, and the carbon fiber bundle (2A) is fed inthe longitudinal direction while controlling the speed of the fiberbundle. An air flow is blown in a crossing direction while maintaining apredetermined overfeed amount. In a portion where the air flow passes,the carbon fiber bundle (2A) is arcuately strained to be unbound in thewidth direction, and the sizing agent is cooled and hardened, therebyforming the extended fiber-opened sheet (2B).

As shown in FIG. 6, next, the fiber-opened sheet (2B) is laid on oneface of the strip-like expanded graphite (3) having a width (W2)=25.00mm and a thickness (T2)=0.25 mm, to form the base member (4) in whichthe sheet-like reinforcing member (20) configured by the carbon fibers(2) is disposed on one face of the strip-like expanded graphite (3).

Then, the base member (4) is stranded to be formed into the cord-likemember (40), thereby producing the gland packing material (1).

Preferably, an adhesive agent is omitted in the base member (4).However, the coupling force between the reinforcing member (20) and thestrip-like expanded graphite (3) may be enhanced by using a small amountof adhesive agent. Specifically, as shown in FIG. 7, for example, anadhesive agent (6) of epoxy resin, acrylic resin, phenol resin, or likeresin may be disposed in a spot-like manner on one face of thestrip-like expanded graphite (3) having a width (W2)=25.00 mm and athickness (T2)=0.25 mm, and the fiber-opened sheet (2B) may be laid onone face of the strip-like expanded graphite (3) in this state to formthe base member (4). The adhesive agent (6) is used in a spot-likemanner so that the used amount is restricted to a very small level.Therefore, the properties of the strip-like expanded graphite (3) suchas the affinity and the compression recovery property are prevented frombeing lowered by hardening of the adhesive agent (6).

Alternatively, as shown in FIGS. 8 and 9, for example, the base member(4) may be formed by, when expanded graphite powder is to becompression-molded to the strip-like expanded graphite (3), disposingthe reinforcing member (20) to be integrated with one face of thestrip-like expanded graphite (3). Specifically, as shown in FIG. 8,expanded graphite powder (3A) is superimposed on the fiber-opened sheet(2B) having a width (W1)=25.00 mm and a thickness (T1)=0.03 mm. Acompression-molding process is then applied, thereby forming the basemember (4) in which, as shown in FIG. 9, the reinforcing member (20)configured by the fiber-opened sheet (2B) is disposed on one face of thestrip-like expanded graphite (3) that is compressed so as to have awidth (W2)=25.00 mm and a thickness (T2)=0.25 mm.

In the first embodiment, the reinforcing member (20) constituting thebase member (4), and the strip-like expanded graphite (3) are formed soas to have the same width. In the invention, alternatively, their widthsmay be different from each other.

In a first modification shown in FIG. 10, for example, the base member(4) is formed by laying the fiber-opened sheet (2B) which is smaller inwidth than the strip-like expanded graphite (3), on one face of thestrip-like expanded graphite (3).

In a second modification shown in FIG. 12, the base member (4) is formedby laying the fiber-opened sheet (2B) which is larger in width than thestrip-like expanded graphite (3), on one face of the strip-like expandedgraphite (3). In the second modification, when both end portions in thewidth direction of the fiber-opened sheet (2B) protrude from thestrip-like expanded graphite (3), one of the protruding end portions ofthe fiber-opened sheet (2B) is exposed to the outside of the cord-likemember (40). Among the end portions in the width direction of thestrip-like expanded graphite (3), therefore, the end portion which isopposite to one end portion (5) that is to be involved in the cord-likemember (40) is preferably aligned with the end portion in the widthdirection of the fiber-opened sheet (2B) as indicated by the phantomline in FIG. 12.

In a third modification shown in FIG. 13, the base member (4) is formedby laying a small-width fiber-opened sheet (2B) on both faces of thestrip-like expanded graphite (3). In this case, when the base member (4)is stranded, one of the fiber-opened sheets (2B) may be exposed to theoutside of the cord-like member (40). Therefore, it is preferable toform the one fiber-opened sheet (2B) in a portion close to one end inthe width direction of the strip-like expanded graphite (3) so that,when the base member (4) is stranded, the sheet is involved in thecord-like member (40).

It is a matter of course that, in the fibrous material and thestrip-like expanded graphite which are used in the invention, thethickness of the fibers, the number of the bundled fibers, the width ofthe sheet, the thickness of the sheet, the width and thickness of thestrip-like expanded graphite, and the like are not restricted to thosein the first embodiment described above.

As the carbon fibers (2), however, it is preferable to use fibers eachhaving a diameter of 3 μm to 15 μm. When the diameter is smaller than 3μm, the fibers may be broken during the stranding process, and, when thediameter is larger than 15 μm, the fibers are hardly stranded.Therefore, it is most preferable to set the diameter of the carbonfibers (2) to a range of 5 μm to 9 μm. In the invention, in place ofcarbon fibers, other brittle fibers, or tough fibers may be used. In thecase where tough fibers such as metal fibers are used, such fibers havehigh bendability, and hence it is less likely that they are brokenduring the stranding process. In such a case, therefore, thinner fibersmay be used.

Moreover, the thickness (T1) of the fiber-opened sheet (2B) ispreferably set to a range of 10 μm to 300 μm, and more preferably to arange of 30 μm to 100 μm. When the thickness (T1) is smaller than 10 μm,the internal reinforcement effect is reduced, and a uniform sheet ishardly produced. When the thickness (T1) is larger than 300 μm, theinternal reinforcement effect can be enhanced, but the stranding processis hardly applied.

FIG. 13 is a perspective view showing a second embodiment of the glandpacking material of the invention. The gland packing material (1) of thesecond embodiment is configured by the cord-like member (40) which, asshown in FIG. 13, is formed by winding the base member (4) that isconfigured in the same manner as the first embodiment described above,about the longitudinal direction in the state where the strip-likeexpanded graphite (3) is directed outward and the reinforcing member(20) configured by the carbon fibers (2) is directed inward. The carbonfibers (2) are placed in parallel with the longitudinal direction of thecord-like member (40), and the whole reinforcing member (20) configuredby the carbon fibers (2) is placed together with the one end portion (5)in the width direction of the strip-like expanded graphite (3) insidethe cord-like member (40).

Namely, the cord-like member (40) is in the state where a portion of thestrip-like expanded graphite (3) is placed in the whole outer side, andthe reinforcing member (20) is covered by the strip-like expandedgraphite (3), and, in the same manner as the first embodiment, the glandpacking material (1) is configured to have an internal reinforcementstructure in which the sheet-like reinforcing member (20) is interposedbetween the strip-like expanded graphite (3).

The other configuration is similar to that of the first embodiment, andfunctions in a similar manner. Therefore, its description is omitted.

When the gland packing material (1) of the second embodiment is strandedin a spiral manner, the material can be formed into the gland packingmaterial (1) having an appearance which is identical with that of thefirst embodiment, and function and attain effects in a similar manner asthe first embodiment.

FIGS. 14 and 15 show a third embodiment of the invention.

In both the first and second embodiments described above, the strip-likeexpanded graphite (3) is disposed only on one face of the reinforcingmember (20). By contrast, in the third embodiment, as shown in FIG. 14,the base member (4) is formed by disposing the strip-like expandedgraphite (3) having a width which is equal to that of the reinforcingmember (20) configured by the fiber-opened sheet (2B), on the both facesof the reinforcing member (20).

In the same manner as the first embodiment described above, the basemember (4) is stranded in the longitudinal direction with starting froman end, whereby the gland packing material (1) configured by thecord-like member (40) is formed as shown in FIG. 15.

In the third embodiment, since the strip-like expanded graphite (3) isdisposed on the both faces of the reinforcing member (20) configured bythe carbon fibers (2), a double structure in which the strip-likeexpanded graphite (3) sandwiches the reinforcing member (20) is formed,and hence the properties which are preferable in sealing, such as thecompressibility and the recovery property are further improved, so thata higher sealing property can be obtained. Since the strip-like expandedgraphite (3) is disposed on the both faces of the reinforcing member(20), the contact area between the reinforcing member (20) and thestrip-like expanded graphite (3) is widened. As a result, the couplingforce between the strip-like expanded graphite (3) and the reinforcingmember (20) can be further enhanced through the many openings (20A)disposed in the reinforcing member (20).

The other configuration is similar to that of the first embodiment, andfunctions in a similar manner. Therefore, its description is omitted.

In the base member (4) used in the third embodiment, in the same manneras the first embodiment described above, the widths of the reinforcingmember (20) and the strip-like expanded graphite (3) may be differentfrom each other.

In a first modification of the third embodiment shown in FIG. 16,namely, the base member (4) is formed by laying the strip-like expandedgraphites (3) which are larger in width than the fiber-opened sheet(2B), respectively on the both faces of the fiber-opened sheet (2B).

In a second modification of the third embodiment shown in FIG. 17, thebase member (4) is formed by laying the strip-like expanded graphites(3) which are smaller in width than the fiber-opened sheet (2B),respectively on the both faces of the fiber-opened sheet (2B) In thesame manner as the second modification of the first embodiment, one endportion in the width direction of the strip-like expanded graphite (3)which is on the outer side is preferably aligned with the end portion inthe width direction of the fiber-opened sheet (2B) as indicated by thephantom line in FIG. 17.

In the invention, it is a matter of course that, when the strip-likeexpanded graphites (3) are to be disposed respectively on the both facesof the reinforcing member (20), any combination of two kinds oflarge-width strip-like expanded graphite, small-width strip-likeexpanded graphite, and equal-width strip-like expanded graphite can beused.

FIG. 18 is a perspective view showing a fourth embodiment of the glandpacking material of the invention. The gland packing material (1) of thefourth embodiment is configured by the cord-like member (40) which isformed by winding the base member (4) that is configured in the samemanner as the third embodiment described above, about the longitudinaldirection. The carbon fibers (2) are placed in parallel with thelongitudinal direction of the cord-like member (40). The otherconfiguration is similar to that of the third embodiment, and functionsin a similar manner. Therefore, its description is omitted.

In the embodiments described above, carbon fibers are used as thefibrous material. In the invention, alternatively, other brittle fibers,and tough fibers may be used. Examples of such brittle fibers are glassfibers such as E-glass, T-glass, C-glass, and S-glass, silica fibers,and ceramic fibers such as alumina and alumina-silica. Examples of thetough fibers are metal fibers such as stainless steel, aramid fibers,and PBO fibers.

Although a fiber-opened sheet is used as the sheet configured by afibrous material, the fibrous material which is useful in the inventionmay be formed into a sheet-like shape by other means.

Next, the gland packing of the invention which is produced with usingthe gland packing material will be described.

FIG. 19 is a perspective view showing an embodiment of the gland packingof the invention.

The cord-like gland packing (8) is produced by preparing a plurality ofthe above-described gland packing materials (1) of the invention, andbundling and braiding these gland packing materials (1) by a braidingmachine. For example, the gland packing (8) shown in FIG. 20 is producedby conducting an eight-strand square-knitting process on eight glandpacking materials (1).

The cord-like gland packing (8) is produced with using a plurality ofthe above-described gland packing materials (1) which have a highsealing property and an excellent shape-retaining property, whereby theexpanded graphite is prevented from dropping off during the braidingprocess. As a result, in the gland packing (8), the elasticity is notreduced, the properties which are preferable in sealing, such as thecompressibility and the recovery property are held, and the sealingproperty is improved. In the case where the packing is compressed or apressure is applied to the packing, movement of expanded graphiteparticles is suppressed. Therefore, the sealing face pressure isprevented from being lowered, so that the pressure resistanceperformance is improved, and the pressure contact force to be applied tothe counter member is kept to a high level, so that the sealing propertyis improved. As a result, the gland packing (8) can satisfactorily seala shaft seal part of a fluid apparatus or the like.

In the gland packing material (1), moreover, the used amount of theadhesive agent is zero or a very small amount. Even when the glandpacking (8) is used under a high temperature condition, therefore,reduction of the sealing property due to burning of the adhesive agentcan be suppressed. Also because of this, the gland packing has anexcellent sealing property.

FIG. 20 is a perspective view showing another embodiment of the glandpacking of the invention.

In the embodiment, the cord-like gland packing (8) is produced by, inplace of braiding gland packing materials (1), bundling and twisting aplurality of gland packing materials (1). For example, the gland packing(8) shown in FIG. 20 is formed by conducting a roll molding processwhile bundling and applying a twisting process on six gland packingmaterials (1).

The gland packing (8) of the embodiment functions and attains effects ina similar manner as the embodiment in which the gland packing materials(1) are braided. Therefore, its description is omitted.

1. A gland packing material wherein said gland packing material is configured by a cord-like member (40) which is formed by stranding a strip-like base member (4), or winding a strip-like base member (4) about a longitudinal direction, or winding a strip-like base member (4) about a longitudinal direction and then stranding said base member, said base member (4) comprises: a sheet-like reinforcing member (20) configured by a fibrous material (2); and a strip-like expanded graphite (3), said strip-like expanded graphite (3) is disposed at least on one face of said reinforcing member (20), a portion of said strip-like expanded graphite (3) is placed outside said cord-like member (40), said reinforcing member (20) is involved in said cordlike member (40), a large number of openings (20A) are formed in said reinforcing member (20), and said strip-like expanded graphite (3) faces said openings (20A).
 2. A gland packing material according to claim 1, wherein a whole outside of said cord-like member (40) is covered by said strip-like expanded graphite (3).
 3. A gland packing material according to claim 1, wherein said strip-like expanded graphite (3) is disposed only on one face of said reinforcing member (20).
 4. A gland packing material according to claim 1, wherein said strip-like expanded graphite (3) is disposed on both faces of said reinforcing member (20).
 5. A gland packing material according to claim 1, wherein said fibrous material (2) is configured by a fiber-opened sheet (2B) in which multifilament yarns are opened in a sheet-like shape.
 6. A gland packing material according to claim 5, wherein a thickness of said fiber-opened sheet (2B) is set to 10 μm to 300 μm.
 7. A gland packing material according to claim 1, wherein said fibrous material (2) is configured by one or two or more selected from the group consisting of carbon fibers and other brittle fibers, and tough fibers.
 8. A gland packing material according to claim 7, wherein said brittle fibers are configured by one or two or more selected from the group consisting of glass fibers, silica fibers, and ceramic fibers.
 9. A gland packing material according to claim 7, wherein said tough fibers are configured by one or two or more selected from the group consisting of metal fibers, aramid fibers, and PBO fibers.
 10. A gland packing wherein a plurality of gland packing materials (1) according to any one of claims 1 to 9 are used, and braided or twisted. 